JP7359157B2 - heads up display - Google Patents

Description

The present invention relates to a head-up display mounted on a vehicle or the like.

A head-up display is mounted on a vehicle and displays information necessary for driving to the driver as a virtual image through a transmissive and reflective part such as a windshield. As a result, the head-up display can display information superimposed on the scenery in front of the vehicle, and the driver can grasp necessary information without having to make large line-of-sight movements while driving.

Conventionally, in order to prevent display light from being unintentionally reflected by non-relay optical systems such as plane mirrors and concave mirrors, and from deteriorating the display quality of the virtual image seen by the viewer, a reflection reduction layer has been provided inside the case. is known (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2015-64396

The reflection reducing layer is formed by applying, pasting, printing, etc. a substance having low reflectance. However, providing a reflection reducing layer using these methods has led to an increase in the manufacturing process and manufacturing cost. Further, since the purpose of the reflection-reducing layer is to reduce reflection, there is a possibility that unintended slight reflections may be seen by a viewer in a dark environment such as at night.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a head-up display that can improve the display quality of virtual images.

In order to solve the above-mentioned problems, a head-up display according to the present invention includes a display device that outputs display light, a plane mirror that reflects the display light output from the display device, and a head-up display that reflects the display light reflected by the plane mirror. a case that has a reflective concave mirror and an internal space in which an optical path of the display light reflected by the plane mirror is formed, and has a first bottom surface facing the optical path and a second bottom surface other than the first bottom surface; The bottom surface has a reflection structure that reflects at least the display light reflected by the plane mirror in a direction other than the concave mirror.
The reflective structure has a structure in which a plurality of protrusions are lined up at a predetermined pitch.
The reflective structure satisfies p=h/tanθ, where the incident angle of the display light that is incident on the reflective structure and reflected by the plane mirror is defined as θ, the height of the protruding portion is defined as h, and the pitch is defined as p. .

In the head-up display according to the present invention, the display quality of virtual images can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of an embodiment of a head-up display according to the present invention, illustrating the overall configuration. An overhead view of the head-up display with the upper case and transparent cover removed. FIG. 3 is an explanatory diagram for explaining the effect of the shielding wall, and shows a case where the shielding wall is parallel to the perpendicular to the optical axis. FIG. 3 is an explanatory diagram for explaining the effect of the shielding wall, and shows a case where the shielding wall has an inclination with respect to the perpendicular to the optical axis. A cross-sectional view taken along the line IV-IV in FIG. 2.

Embodiments of a head-up display according to the present invention will be described based on the accompanying drawings. The head-up display according to the present invention is mounted, for example, on a vehicle such as an automobile.

FIG. 1 is an external perspective view of an embodiment of a head-up display according to the present invention, illustrating the overall configuration.

FIG. 2 is an overhead view of the head-up display 1 with the upper case 11 and the transparent cover 18 removed.

A head-up display 1 (HUD1) is arranged in an instrument panel of an automobile. The HUD 1 mainly includes a display device 3, a plane mirror 4, a concave mirror 5, a case 6, and a control board (not shown). The HUD 1 reflects display light L1 representing a display image displayed by the display device 3 by a plane mirror 4 and a concave mirror 5 that constitute a relay optical system, and irradiates it onto a windshield of an automobile, which is an example of a transmissive reflective section. A viewer (mainly a driver) can visually recognize the virtual image of the display image superimposed on the actual scene in front of the vehicle.

The display device 3 outputs display light L1. The display device 3 is, for example, a TFT (Thin Film Transistor) type liquid crystal display device. The display device 3 may include a projector and a screen forming a display surface.

The plane mirror 4 includes a base material made of, for example, a synthetic resin material, and a reflective film formed on the surface of the base material by vapor deposition or the like. The plane mirror 4 reflects the display light L1 output from the display device 3 toward the concave mirror 5.

The concave mirror 5 includes a base material made of, for example, a synthetic resin material, and a reflective film formed on the surface of the base material by means such as vapor deposition. The concave mirror 5 reflects the display light L1 reflected by the plane mirror 4 toward the windshield. The concave mirror 5 has a function as a magnifying glass, and magnifies the displayed image and reflects it onto the windshield. Thereby, the viewer views a virtual image in which the displayed image is enlarged. The concave mirror 5 is rotated around a rotation axis by an actuator 8. The actuator 8 adjusts the angle of the concave mirror 5 by rotating the concave mirror 5, adjusts the irradiation position of the display light L1, and adjusts so that external light is not reflected by the concave mirror 5 and directed toward the display device 3. .

The case 6 includes an upper case 11 and a lower case 12, which are made of, for example, a black synthetic resin with light-shielding properties. The case 6 has an internal space 13 that accommodates the display device 3, the plane mirror 4, and the concave mirror 5 by combining the upper case 11 and the lower case 12.

The lower case 12 has a structure for mainly attaching the display device 3, the plane mirror 4, the concave mirror 5, and the control board. In addition, the lower case 12 (case) is the optical path of the display light L1 reflected by the plane mirror 4, and has a first bottom surface 15 facing the optical path formed in the internal space 13 and a second bottom surface 16 other than that. have In addition, in FIG. 2, the first bottom surface 15 is a surface surrounded by a dotted line d.

The lower case 12 has a reflective structure 30 provided on the first bottom surface 15 and a shielding wall 20 provided on the second bottom surface 16. Details of the reflection structure 30 and the shielding wall 20 will be described later.

Upper case 11 has an opening 17 . The opening 17 is provided in a portion facing the windshield. The opening 17 is covered with a light-transmitting cover 18 having light-transmitting properties.

The control board is a printed circuit board on which a control section for controlling the operation of the display device 3 and the like is mounted. The control unit includes, for example, a microcomputer having a storage device and an arithmetic unit. The control unit causes the display device 3 to display a display image by causing the arithmetic device to perform appropriate calculations based on various vehicle information acquired from the in-vehicle network and various sensors and according to an operation program stored in advance in the storage device. The control board is fixed outside the internal space 13 of the lower case 12.

Next, details of the shielding wall 20 of the lower case 12 will be explained.

The shielding wall 20 is provided on the second bottom surface 16 between the display device 3 and the plane mirror 4. The shielding wall 20 surrounds the front side of the display device 3 without blocking the display light L1 emitted from the display screen of the display device 3. Thereby, the shielding wall 20 prevents the display device 3 from being visually recognized from outside the HUD 1. The shielding wall 20 has a wall surface 21 that is inclined with respect to a perpendicular to the optical axis of the display light L1 output from the display device 3.

The wall surface 21 is the surface of the shielding wall 20 on the plane mirror 4 side, and is oriented in such a direction that the plane mirror 4 does not reflect back the light (display light L1 and external light) that is unintentionally reflected toward the display device 3 side. The optical path of the display light L1 reflected by the plane mirror 4 on the first bottom surface 15 is tilted in a direction such that the display light L1 is not reflected toward the area where it is located. That is, the wall surface 21 has an inclination such that it faces the side surface 19 of the lower case 12. The inclination is, for example, about 0.1 degrees to 5 degrees.

Here, FIGS. 3 and 4 are explanatory diagrams for explaining the action of the shielding wall 20. FIG. 3 shows a case where the shielding wall 20 is parallel to the perpendicular to the optical axis A. FIG. 4 shows a case where the shielding wall 20 has an inclination with respect to the perpendicular to the optical axis A.

For example, when the external light L2 transmitted through the transparent cover 18 is reflected by the concave mirror 5 and directed toward the plane mirror 4, the plane mirror 4 further reflects this external light L2 toward the display device 3 side. Since there is a shielding wall 20 between the plane mirror 4 and the display device 3, the shielding wall 20 further reflects the external light L2.

At this time, as shown in FIG. 3, if the shielding wall 20 (wall surface 21) is parallel to the perpendicular to the optical axis A (perpendicular to the optical axis A), the wall surface 21 The external light L2 traveling along the optical axis A is reflected again along the optical axis A. Therefore, the reflected light L3 travels to the plane mirror 4 again. The reflected light L3 is sequentially reflected by the plane mirror 4, the concave mirror 5, and the windshield, causing the viewer to view an unintended virtual image.

On the other hand, as shown in FIG. 4, when the shielding wall 20 (wall surface 21) has an inclination with respect to the perpendicular to the optical axis A, the wall surface 21 directs the external light L2 toward the side surface 19 side of the lower case 12 or the upper case 11 side. reflect. Therefore, the reflected light L3 does not proceed to the plane mirror 4 side. Therefore, the reflected light L3 will not enter the optical path side of the display light L1 and will not cause an unintended virtual image to be viewed.

Next, details of the reflective structure 30 of the lower case 12 will be explained.
FIG. 5 is a sectional view taken along line IV-IV in FIG. 2.

The reflective structure 30 has a concave bottom surface 31 , a plurality of protrusions 32 , and a reflective surface 33 . It is preferable that the reflective structure 30 is formed integrally with the lower case 12, for example, when the lower case 12 is formed by injection molding. As shown in FIG. 2, the reflective structure 30 only needs to be provided on at least a portion of the first bottom surface 15, and does not need to be provided on the entire surface of the first bottom surface 15. The reflection structure 30 may be provided in a region where the display light L1 reflected by the plane mirror 4 is likely to enter, for example, by simulation or the like.

The concave bottom surface 31 is a surface that is one step lower (concave in the -Z direction) in the first bottom surface 15. The convex portion 32 is a ridge (linear convex portion) that protrudes from the concave bottom surface 31 and extends in a direction substantially perpendicular to the optical axis of the display light L1. The tip of the protruding portion 32 is on the same plane as the bottom surface of the lower case 12 where the reflective structure 30 is not provided. That is, the concave bottom surface 31 is a portion recessed from the first bottom surface 15 in order to allow the protruding stripes 32 to protrude, and the protruding stripes 32 do not protrude from the bottom surface of the lower case 12 . The reflective surface 33 is an inclined surface formed on the top of the protruding strip 32 . The reflective surface 33 has an inclination of, for example, 45 degrees. The reflective surface 33 (reflective structure) reflects the display light L4 that is reflected by the plane mirror 4 and advances toward the first bottom surface 15 at least in a direction other than the concave mirror 5. The direction other than the concave mirror 5 is, for example, a direction other than the direction of the concave mirror 5 and the plane mirror 4, such as the upper case 11 side or the lower case 12 side (side surface 19 side), and a direction that does not interfere with the display light L1 appropriately emitted from the HUD 1. It may be in any direction.

The pitch p of the protrusions 32 and the reflective surface 33 is determined by the incident angle θ of the display light L4 entering the first bottom surface 15 obtained by simulation, etc., and the height h of the protrusions 32 designed from various conditions. It is determined. That is, by determining the pitch p so that the pitch p=height h/tanθ is satisfied, the display light L4 traveling toward the concave bottom surface 31 can be reflected on the reflective surface 33 without being reflected on the concave bottom surface 31.

In addition, in FIG. 5, the reflective surface 33 is formed over the entire height h of the protruding line part 32, but it may be formed in a part of the top side of the height h of the protruding line part 32.

Such a HUD 1 has a reflective structure 30 on the first bottom surface 15. Thereby, the HUD 1 can reduce the display light L4 that unintentionally advances toward the first bottom surface 15 from being reflected toward the concave mirror 5 side. For example, it is easier to manufacture the HUD 1 (lower case 12) than in the case where a reflection reduction layer is provided using a substance with low reflectance, and the display light L4 itself is transferred to the concave mirror 5 in the first place instead of reducing the reflectance. I won't let you proceed. Therefore, the HUD 1 can prevent unintended light from reaching the windshield and forming a virtual image. Therefore, the HUD 1 can improve the display quality of the virtual image visually recognized by the viewer.

Moreover, since the HUD 1 has the shielding wall 20, the display quality of the virtual image can be further improved due to the synergistic effect with the reflection structure 30.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.
For example, the protruding portion and the reflective surface may be provided on the first bottom surface. That is, it is not essential to form a concave bottom surface.

1 Head-up display 3 Display device 4 Plane mirror 5 Concave mirror 6 Case 8 Actuator 11 Upper case 12 Lower case 13 Internal space 15 First bottom surface 16 Second bottom surface 17 Opening 18 Transparent cover 19 Side surface 20 Shielding wall 21 Wall surface 30 Reflection structure 31 Concave bottom surface 32 Convex strip 33 Reflective surface A Optical axis L Display light L1, L4 Display light L2 External light L3 Reflected light d Dotted line h Height p Pitch θ Incident angle

Claims (4)

a display device that outputs display light;
a plane mirror that reflects display light output from the display device;
a concave mirror that reflects the display light reflected by the plane mirror;
a case having an internal space in which an optical path of display light reflected by the plane mirror is formed, and a case having a first bottom surface facing the optical path and a second bottom surface other than the first bottom surface,
The first bottom surface has a reflection structure that reflects the display light reflected by the plane mirror in a direction other than the concave mirror at least ,
The reflective structure has a structure in which a plurality of protrusions are lined up at a predetermined pitch,
When the reflection structure is defined as: the incident angle of the display light reflected by the plane mirror that enters the reflection structure is defined as θ, the height of the protrusion is defined as h, and the pitch is defined as p;
A head-up display that satisfies p=h/tanθ . the first bottom face faces an optical path from the plane mirror to the concave mirror;
A head-up display according to claim 1. The head-up display according to claim 2, wherein the protruding portion is formed on a concave bottom surface that is recessed from the first bottom surface. A shielding wall provided on the second bottom surface between the display device and the plane mirror, the shielding wall having an inclination of 0.1 degrees to 5 degrees with respect to a perpendicular to the optical axis of display light output from the display device. The head-up display according to claim 1, further comprising a shielding wall having a wall surface.

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